Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.
Well below target. Risk of deficiency symptoms tied to bone · muscle.
Below the recommended daily target. Long-term adequacy not assured.
Daily target met. Standard nutritional support for bone · muscle.
Common for specific health goals. Check the evidence for your situation before sustaining this level.
Above the tolerable upper limit. Risk of adverse effects — back off or consult a clinician.
You're at 0% of your calcium target. The biggest single-serving sources to top it off:
Most abundant mineral in the human body — 99% stored in bones and teeth as hydroxyapatite. The remaining 1% in blood and soft tissue is tightly regulated (parathyroid hormone, calcitonin, calcitriol) because of its central role in muscle contraction, nerve signalling, and coagulation.
Bone serves as the calcium bank. When serum calcium drops, parathyroid hormone (PTH) increases bone resorption, renal reabsorption, and (via calcitriol) gut absorption. Chronic dietary insufficiency forces ongoing bone withdrawal, driving osteopenia and osteoporosis over decades. Adequate vitamin D and a sufficient bone-calcium reservoir established by young adulthood are the levers that matter.
Frank hypocalcemia is uncommon (homeostasis maintains serum) but inadequate intake drives long-term bone loss without acute symptoms. ~40% of US adults fail to meet RDA.
Excess from supplements (not food) may increase cardiovascular event risk and kidney stones. Food calcium does not show this association.
Calcium citrate absorbs equally well with or without food and is preferred for older adults on PPIs. Calcium carbonate is cheaper but needs stomach acid to absorb — take with meals. Avoid single doses above 500 mg of elemental calcium; absorption efficiency drops sharply. Pair with vitamin D for full benefit.
Active absorption is vitamin-D-dependent (duodenum); passive paracellular absorption (jejunum/ileum) dominates above ~10% saturation. Absorption efficiency drops with dose — 500 mg cap per sitting is the practical ceiling. Phytate (whole grains), oxalate (spinach, rhubarb), and high-dose iron all reduce uptake. Bioavailability from low-oxalate greens (kale, bok choy) is actually higher than from milk.
Adequacy through midlife builds the bone reserve drawn down by aging. Post-menopause, calcium + D + resistance exercise + K2 cooperate to slow loss. Pure calcium-mega-dose supplementation without other co-factors may shift cardiovascular risk — total intake (food + supplement) should aim at RDA, not greatly exceed it.
Bone mineralization, muscle contraction, neuronal signaling.
Forms with lower absorption: carbonate. Prefer better-absorbed forms when supplementing.
The mechanisms and systems this nutrient feeds. Click any to drill into what runs on it.
Whole foods that contribute meaningfully (≥10% DV per 100 g serving). Click any food to see its full nutrient profile and what else it brings to the table.
See all foods high in Calcium, ranked →